According to Bild (h/t Sport Witness) the German champions are considering moving on a number of players after their difficult start to the season, including the experienced centre-back.

Bild reports the Red Devils are "thought to be interested" in Boateng after trying to sign him in the summer transfer window. The German publication added there is a 70 per cent chance of the former Manchester City man ending up at Old Trafford.

It's noted the transfers of some key figures in the Bayern dressing room will likely happen at the end of the season, with the club reportedly concerned about the amount of power some star players hold. Per Kicker (h/t ESPN FC's Stephen Uersfeld), there are a number of stars unhappy with the work being done by manager Nico Kovac.

Bayern have endured a testing beginning to the 2018-19 campaign. They sit seven points behind league leaders Borussia Dortmund after a thrilling 3-2 loss on Saturday at the Westfalenstadion.

At the moment, a number of players aren't performing to their usual level, while there are a number of stars—including Franck Ribery and Boateng—who are approaching the twilight of their careers.

Journalist Keith Costigan commented on how Boateng struggled along with his defensive partner Mats Hummels in Saturday's loss, as well as earlier in the campaign:

keith costigan @KeithCostigan

Sule didn’t start but his absence only helped showcase how important he now is to Bayern. Both Hummels and Boateng out of sorts. Unfair to blame all this on Kovac too. Heynckes only papered over obvious cracks last campaign

keith costigan @KeithCostigan

Jerome Boateng has been absolutely dreadful dating back to end of last season. Think Bayern will regret not cashing in on him when they had the chance to

At the peak of his powers, Boateng was rated as one of the best defenders in the world. The Bayern man had it all, as he was physical, dynamic and switched on in his duties at the back.

The Germany international was also adept at playing out from deep, meaning he excelled during Pep Guardiola's tenure at the club. Unfortunately for him, a number of injury issues mean he has been sidelined frequently in recent years.

Over the course of the last couple of seasons, there have been signs that those persistent knocks have started to catch up with Boateng. Not only has he been below par for Bayern, at the FIFA World Cup in the summer he appeared a long way off the pace.

Per Goal's Ronan Murphy, he was left out of the Germany squad for the upcoming international break:

Ronan Murphy @swearimnotpaul

DFB update: Ter Stegen left out of Germany squad to allow him to recover from a shoulder problem. Boateng given "a break." #DFB #DieMannschaft

Samuel Luckhurst of the Manchester Evening News wasn't impressed with how Boateng performed in a recent outing for Germany:

Samuel Luckhurst @samuelluckhurst

Watching Jerome Boateng against Netherlands, it is just as well #mufc had him low down on their defensive targets list. Every right to disregard him as a serious target, though he should never have been considered in the first place.

While Boateng was once a force of nature at the back, his recent struggles and his poor fitness record would make him a strange acquisition by United. If Mourinho is to spend big money on bolstering his defence, he'd be better served signing a player whose career remains on an upward trajectory.